A New Method to Analyze Spatial Binary Mechanisms With Spherical Pairs

2006 ◽  
Vol 129 (4) ◽  
pp. 455-458 ◽  
Author(s):  
Psang Dain Lin ◽  
Jung-Fa Hsieh
Keyword(s):  
New Method ◽  
Free Region ◽  
Analysis And Synthesis ◽  
Independent Parameters

One of the most popular mathematical tools in the fields of robotics and mechanisms is the Denavit-Hartenberg (DH) notation (Denavit and Hartenberg, 1955, J. Appl. Mech., 77, pp. 215–221). It is valid only for mechanisms containing prismatic, revolute, helical, and cylindrical pairs, but cannot be applied to spherical pairs. This paper presents an extended DH notation that includes spherical pairs, consequently allowing the required independent parameters of any spatial binary mechanism to be listed for purposes of analysis and synthesis. Further, the interference-free region with maximum ball-retention capability of a socket in a spherical pair can be determined analytically. Extended DH notation can systematically model arbitrary binary mechanisms with spherical pairs, simplifying their design and study.

The Spatial Linkage Analysis and Synthesis of the Vector Fitting Method

2012 ◽  
Vol 268-270 ◽  
pp. 1231-1238
Author(s):  
You Liang Xu
Keyword(s):  
Linkage Analysis ◽  
Unit Vector ◽  
New Method ◽  
Analysis And Design ◽  
Vector Fitting ◽  
The Core ◽  
Design Variables ◽  
Fitting Method ◽  
Analysis And Synthesis ◽  
Core Idea

Put forward a new method of spatial linkage analysis and synthesis of the vector fitting. The core idea is: all components available in mechanisms can be represent by one or one group of vectors, all vectors are transformed from unit vector, and the mechanism is a assemblage of those vectors. Because of kinematic variables (position, direction, changing when moving ) and design variables (shape, size, unchanging when moving ) is been properly separated which can improve the efficiency of analysis and calculation. The example shows that the method is efficient, and can be used both in the analysis and design of the mechanism.

Stability of General Hill’s Equation With Three Independent Parameters

1972 ◽  
Vol 39 (1) ◽  
pp. 276-278 ◽  
Author(s):  
K. Hamer ◽  
M. R. Smith
Keyword(s):  
Perturbation Method ◽  
New Method ◽  
Order Of Approximation ◽  
Hill’S Equation ◽  
Stability Boundaries ◽  
First Order ◽  
Hill's Equation ◽  
The Stability ◽  
Independent Parameters

The stability of Hill’s equation with three independent parameters, two of which are small, is analyzed using a perturbation method. It is shown that, except for periodic terms of a special type, existing methods of determining stability boundaries fail. A new method, which works successfully to the first order of approximation, is described.

scholarly journals Topological invariants for superconducting cosmic strings

2018 ◽  
Vol 33 (27) ◽  
pp. 1850156 ◽  
Author(s):  
Xinfei Li ◽  
Xin Liu
Keyword(s):  
Complex System ◽  
Cosmic Strings ◽  
Topological Invariant ◽  
New Method ◽  
Topological Invariants ◽  
Linking Number ◽  
Line Defects ◽  
Chern Simons ◽  
Independent Parameters ◽  
Knot Polynomial

Superconducting cosmic strings (SCSs) have received revived interests recently. In this paper we treat closed SCSs as oriented knotted line defects, and concentrate on their topology by studying the Hopf topological invariant. This invariant is an Abelian Chern–Simons action, from which the HOMFLYPT knot polynomial can be constructed. It is shown that the two independent parameters of the polynomial correspond to the writhe and twist contributions, separately. This new method is topologically stronger than the traditional (self-)linking number method, which fails to detect essential topology of knots sometimes, shedding new light upon the study of physical intercommunications of superconducting cosmic strings as a complex system.

Modeling of Dynamic Systems Using Orthogonal Endocrine Adaptive Neuro-Fuzzy Inference Systems

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Marko Milojković ◽  
Dragan Antić ◽  
Miroslav Milovanović ◽  
Saša S. Nikolić ◽  
Staniša Perić ◽  
...  
Keyword(s):  
Dynamic Systems ◽  
Fuzzy Inference ◽  
New Method ◽  
Fuzzy Inference Systems ◽  
Orthogonal Functions ◽  
Real Environment ◽  
Hormonal Effect ◽  
Neuro Fuzzy ◽  
Analysis And Synthesis ◽  
Inference Systems

This paper presents a new method for designing adaptive neuro-fuzzy inference systems (ANFIS). Improvements are made by introducing specially developed orthogonal functions into the very structure of ANFIS, specifically, into the layer that imitates Sugeno stile defuzzification. These functions are specially tailored for analysis and synthesis of dynamic systems and they also contain an adaptive measure of the variability of the systems operating in a real environment, which can be implemented inside the ANFIS as hormonal effect.

Detection of Isomorphism Between Planar Kinematic Chains

1987 ◽  
Author(s):  
L. K. Patel ◽  
A. C. Rao
Keyword(s):  
Graph Theory ◽  
Structural Analysis ◽  
Efficient Method ◽  
Computational Effort ◽  
New Method ◽  
Structural Topology ◽  
Single Degree Of Freedom ◽  
Kinematic Chains ◽  
Single Degree ◽  
Analysis And Synthesis

Abstract Structural analysis and synthesis of linkages is a very important aspect. Detection of isomorphism (equivalent structural topology) is essential to determine structurally distinct chains. Some methods to detect distinct chains and mechanisms have already been developed. These methods besides being falliable, require enormous computational effort and as such necessitate development of an easy and efficient method. This paper presents a new method based on graph theory, for detection of isomorphism among kinematic chains. A probability scheme is attached with the chains and relative loop positions are determined for the chains having identical probability schemes. Isomorphism is detected between planar kinematic chains having single degree of freedom.

NUMERICAL ANALYSIS OF DISPLACEMENTS IN SPATIAL MECHANISMS WITH SPHERICAL JOINTS UTILIZING AN EXTENDED D-H NOTATION

2010 ◽  
Vol 34 (3-4) ◽  
pp. 417-431 ◽  
Author(s):  
Jung-Fa Hsieh
Keyword(s):  
Numerical Analysis ◽  
Translational Motion ◽  
Mechanical Systems ◽  
Kinematic Chains ◽  
Spatial Mechanism ◽  
Spatial Mechanisms ◽  
Spherical Surfaces ◽  
Analysis And Synthesis ◽  
Independent Parameters ◽  
Rotational Freedom

Spherical joints consist of a pair of concave and convex spherical surfaces engaged in such a way as to prevent translational motion of the ball and socket whilst simultaneously allowing three degrees of rotational freedom. The kinematics of spatial mechanisms comprising links and joints are commonly analyzed using the Denavit-Hartenberg (D-H) notation. However, whilst this method allows the kinematics of mechanisms containing prismatic, revolute, helical and cylindrical joints to be explicitly defined, it cannot be directly applied to mechanical systems containing spherical pairs. Accordingly, this paper proposes an extended D-H notation which allows the independent parameters of any spatial mechanism, including one with spherical pairs, to be derived for analysis and synthesis purposes. The validity of the proposed notation is demonstrated via its application to the analysis of mechanisms containing revolute (R), spherical (S), cylindrical (C) and prismatic (P) joints. The results confirm the viability of the extended D-H notation as a means of analyzing the displacements of mechanical systems containing kinematic chains such as RSCR, RSCP, CSSR and CSSP.

Selective Sampling and Orientation of Non-Homogeneous Tissues

1968 ◽  
Vol 26 ◽  
pp. 98-99
Author(s):  
C. C. Clawson ◽  
L. W. Anderson ◽  
R. A. Good
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Random Sampling ◽  
New Method ◽  
Microscope Examination ◽  
Small Areas ◽  
Selective Sampling ◽  
Large Numbers ◽  
Specific Orientation

Investigations which require electron microscope examination of a few specific areas of non-homogeneous tissues make random sampling of small blocks an inefficient and unrewarding procedure. Therefore, several investigators have devised methods which allow obtaining sample blocks for electron microscopy from region of tissue previously identified by light microscopy of present here techniques which make possible: 1) sampling tissue for electron microscopy from selected areas previously identified by light microscopy of relatively large pieces of tissue; 2) dehydration and embedding large numbers of individually identified blocks while keeping each one separate; 3) a new method of maintaining specific orientation of blocks during embedding; 4) special light microscopic staining or fluorescent procedures and electron microscopy on immediately adjacent small areas of tissue.

Characterization of defects in tabular silver halide grains

1990 ◽  
Vol 48 (4) ◽  
pp. 1046-1047
Author(s):  
C. Goessens ◽  
D. Schryvers ◽  
J. Van Landuyt ◽  
A. Verbeeck ◽  
R. De Keyzer
Keyword(s):  
Radiation Damage ◽  
Silver Halide ◽  
Chemical Characteristics ◽  
X Ray ◽  
Free Region ◽  
Central Defect ◽  
Crystallographic Defects ◽  
Physical And Chemical ◽  
Two Sides

Silver halide grains (AgX, X=Cl,Br,I) are commonly recognized as important entities in photographic applications. Depending on the preparation specifications one can grow cubic, octahedral, tabular a.o. morphologies, each with its own physical and chemical characteristics. In the present study crystallographic defects introduced by the mixing of 5-20% iodide in a growing AgBr tabular grain are investigated. X-ray diffractometry reveals the existence of a homogeneous Ag(Br1-xIx) region, expected to be formed around the AgBr kernel. In fig. 1 a two-beam BF image, taken at T≈100 K to diminish radiation damage, of a triangular tabular grain is presented, clearly showing defect contrast fringes along four of the six directions; the remaining two sides show similar contrast under relevant diffraction conditions. The width of the central defect free region corresponds with the pure AgBr kernel grown before the mixing with I. The thickness of a given grain lies between 0.15 and 0.3 μm: as indicated in fig. 2 triangular (resp. hexagonal) grains exhibit an uneven (resp. even) number of twin interfaces (i.e., between + and - twin variants) parallel with the (111) surfaces. The thickness of the grains and the existence of the twin variants was confirmed from CTEM images of perpendicular cuts.

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